The next generation service interface NGSI by the open mobile alliance OMA defines with NGSI 9/10 a data model and a set of interfaces for managing and exchanging context information in a corresponding system. The NGSI 9/10 standard, precisely NGSI context management, Approved version 1.0 of 29 May 2012, for which a PDF copy is available via hypertext transfer protocol (HTTP) at the site technical.openmobilealliance.org/Technical/releaseprogram/docs/NGSI/V1_0-20120529-A/OMA-TS-NGSI_Context_Management-V1_0-20120529-A, is widely adopted in European future internet enablers, for example used by the FI-WARE European internet open API specification available via hypertext transfer protocol secure (HTTPS) at the site forge.fiware.eu/plugins/mediawiki/wiki/fiware/index.php/Summary_of_FI-WARE_Open_Specifications due to its universal applicability for exchange and management of real-world information, especially in the context of the internet-of-things.
The NGSI standard defines a data model to represent context data and a set of operation to exchange this context operation. Conventionally the data model represents all information in terms of entities and attributes. Entities represent arbitrary physical or virtual objects and information about these entities is expressed in form of multiple attributes. For example an entity can represent a room and the indoor temperature of that room could be represented as an attribute.
NGSI 10 operations have the purpose to exchange information about entities and their attributes. Certain operations are defined for that: For example the operation queryContext can be used to query information about a set of attributes and a set of entities. The operation subscribedContext also asks for information but here the information is requested to be updated in regular time intervals or whenever certain conditions are satisfied. The reach of both queries and subscriptions can be limited by restrictions, for example using) (PATH expressions, or so-called operational scopes so that not the whole system executes the query or subscription but only a subsystem. Types of operational scopes predefined in the NGSI 10 standard include geographic scopes that are defined as geographic regions to which the query is to be limited. A further operation defined in the NGSI 10 standard is the updateContext operation which can be used to send new context information to the NGSI system.
One of the universal primitives nowadays that are of greater importance in the multitudes of internet-of-things and machine-to-machine applications is geofencing. Geofencing describes the task to track a movement of a large number of objects in real time, wherein continuously the coordinates of the objects against the set of user defined geofences is evaluated. For each object entering and/or leaving a geofence area a notification is sent by the geofencing system to a subscriber of the geofence. Geofences can be either static, for example a fixed geographic area like a city district or the like or dynamic, i.e. defined in relation to a moving object, for example the periphery of a moving car or the like.
An example for defining geofences is described in WO 2013/058941 A1: Therein a system and method is disclosed for maintaining a geofence to provide alerts in response to an object entering or exiting an area bounded by the geofence. In detail geofencing on mobile devices is described as well a generic method to define geofences.